Reject bids with invalid prev_randao during gossip validation - #5360
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`prev_randao` is deterministic for `parent_block_root`, and the state transition function only allows bids with the correct `prev_randao`. However, gossip rules ignore `prev_randao` and conflate them into a pool keyed by `(bid.slot, bid.parent_block_hash, bid.parent_block_root)`. So, someone who just sends a large bid with wrong `prev_randao` will force smaller bids with correct `prev_randao` to be ignored by spec, while also not allowing inclusion of their bid, i.e., it's unchargeable. Add reject rule to filter incorrect `prev_randao`, the value is known because the rules already require `bid.parent_block_root` to be known in fork choice. Also sync the other missing beacon-chain.md rules to validator.md.
jtraglia
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prev_randao during gossip validation
jtraglia
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Jun 12, 2026
jtraglia
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Jun 12, 2026
jtraglia
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This is a good check to have. Nice catch.
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etan-status
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Jun 16, 2026
When someone sends us a bid with invalid prev_randao but high value, it kicks out the legitimate bid. The invalid one is also non-punishable as it fails subsequent state transition by peers. Add an extra reject rule to filter out invalid prev_randao, there is only a single valid value for each parent block root, and we have efficient functionality in the blockchain_dag to obtain correct RANDAO without expensive state replays. Also proposed for spec inclusion, but we'll need the rule regardless: - ethereum/consensus-specs#5360 Have moved this check to the end, because if the correct value has not yet been cached (i.e., no valid bid received), we may have to load the block from disk (once).
potuz
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Jun 17, 2026
tersec
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Jun 18, 2026
* Reject bids with invalid prev_randao during gossip validation When someone sends us a bid with invalid prev_randao but high value, it kicks out the legitimate bid. The invalid one is also non-punishable as it fails subsequent state transition by peers. Add an extra reject rule to filter out invalid prev_randao, there is only a single valid value for each parent block root, and we have efficient functionality in the blockchain_dag to obtain correct RANDAO without expensive state replays. Also proposed for spec inclusion, but we'll need the rule regardless: - ethereum/consensus-specs#5360 Have moved this check to the end, because if the correct value has not yet been cached (i.e., no valid bid received), we may have to load the block from disk (once). * Apply suggestion from @tersec
nflaig
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Jun 22, 2026
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prev_randaois deterministic forparent_block_root, and the state transition function only allows bids with the correctprev_randao. However, gossip rules ignoreprev_randaoand conflate them into a pool keyed by(bid.slot, bid.parent_block_hash, bid.parent_block_root). So, someone who just sends a large bid with wrongprev_randaowill force smaller bids with correctprev_randaoto be ignored by spec, while also not allowing inclusion of their bid, i.e., it's unchargeable.Add reject rule to filter incorrect
prev_randao, the value is known because the rules already requirebid.parent_block_rootto be known in fork choice.Also sync the other missing beacon-chain.md rules to validator.md.